JP5738880B2 - Offset electrode - Google Patents

Description

  The present invention relates generally to electrode structures, and more particularly to electrodes that are used to supply electrical energy to the skin and that have a design and structure that is particularly suited to resist corrosion.

  Over the years, electrodes have been used to supply electrical energy to the skin for various purposes such as pain management and muscle stimulation. When stimulating electrodes are used for percutaneous applications, they are usually conductive liquids or gels (called “hydrogels”) to provide a continuous and efficient conductive path between the current source and the skin. It is necessary to use Conductive hydrogels generally contain a salt, which is corrosive to common electrode trace materials and can thus adversely affect electrode performance. Thus, in the design of an integral electrode for percutaneous stimulation, in order for such a device to be commercially viable, the electrode must have a sufficiently long shelf life, for which the hydrogel is A design is needed that minimizes or eliminates the ability to move towards and reach the trace element over time.

  One known method of “isolating” the hydrogel from the copper trace at the electrode is to coat the copper with a more corrosion resistant or inert conductive material, such as gold. An example of this is shown in FIG. 1, where the electrode 100 includes a non-conductive substrate 101 (ie, fiberglass) with an opening 102, and a conductive trace material or conductive pad 103 passes through the opening 102 and then into the electrode. It is electrically coupled to an integrated circuit 120 that supplies power. Conductive trace material is also applied over the top surface of the non-conductive substrate. A gold or nickel / gold layer 104 is then applied over the conductive trace element via a well-established ENIG process, isolating the trace material from the hydrogel 105 as described above. To do. While gold is well known to be conductive but inert, it is also well known that it is expensive. Furthermore, although the gold layer theoretically prevents corrosion, in practice, variations and / or imperfections in the manufacturing process, especially thin film technology, can result in varying degrees of corrosion over time, It presents difficult challenges in the design of products that require long-term use and / or long-term storage.

  Other methods are also known that incorporate additional conductive layers between the copper trace material and the hydrogel to prevent or minimize corrosion. This solution is used by Alza Corporation (Mountain View, CA), and an example of such a solution is shown in FIG. The non-conductive substrate 201 of the electrode 200 includes a conductive copper trace material 203 on its upper surface. Deposited on the trace material 203 is one or more additional conductive layers that are inert or more resistant to corrosion, such as conductive tape 206 and silver foil 207. When the electrode is placed on the patient's skin, the hydrogel 205 will be placed between the skin and the additional conductive layer. Incorporating an additional layer between copper and hydrogel does indeed provide an additional corrosion protection effect, but it also increases the electrode material and assembly costs.

  Therefore, there is a need for an improved electrode design that provides sufficient corrosion resistance while reducing materials and assembly costs for use in commercial percutaneous electrode assemblies.

  The present invention comprises a non-conductive substrate comprising a top surface and at least one channel penetrating the non-conductive substrate; and a channel disposed adjacent to at least a portion of the top surface of the non-conductive substrate. And an electrically conductive trace material adapted to be electrically coupled to a power source. The electrode is disposed adjacent to and covering the entire top surface of the trace material, a second conductive material that is inert or more resistant to corrosion than the trace material, and a second conductive material. Inert or more resistant to corrosion than the trace material, located adjacent to the upper surface and covering the entire upper surface and covering a portion of the upper surface of the non-conductive substrate surrounding the second conductive material And a third conductive material. A hydrogel is also disposed adjacent to a portion of the top surface of the third conductive trace material and laterally offset from the trace material.

  The top surface of the non-conductive substrate may include a recess and at least one channel may be disposed in the recess. In yet another embodiment, the conductive trace material may be disposed entirely within the recess, and the second conductive material may also be disposed entirely within the recess.

  In one embodiment, the trace material is made of copper, and in yet another embodiment, the second conductive material is made of gold or gold / nickel. Further, the third conductive material may be manufactured from silver.

  In another alternative embodiment, a foam material may be disposed adjacent to at least a portion of the top surface of the third conductive material so as to substantially surround the hydrogel.

  A non-conductive substrate comprising a top surface, a bottom surface, and at least one channel extending through the non-conductive substrate, wherein the non-conductive substrate is manufactured from a flexible material. Including an electrode is also provided. The electrode further includes a copper trace material disposed adjacent to at least a portion of the top surface of the non-conductive substrate and extending through the channel such that the trace material is electrically coupled to the power source. It is adapted to. The electrode is a second conductive material made from gold or gold / nickel, a second conductive material disposed adjacent to cover the top surface of the trace material, and a second conductive material made from silver. A third conductive material disposed adjacently to cover the top surface of the second conductive material, and the top surface of the third conductive material adjacent to the top surface of the third conductive material. A conductive hydrogel disposed over at least a portion of the hydrogel, wherein the hydrogel is disposed laterally offset from the trace material.

  In one embodiment, the electrode further comprises a foam material that substantially surrounds the hydrogel but leaves the top surface of the hydrogel exposed.

  In yet another embodiment, the top surface of the non-conductive substrate includes a recess and at least one channel is disposed in the recess.

  In an alternative embodiment, the conductive trace material may be disposed in its entirety in the recess and the second conductive material may also be disposed in its entirety in the recess.

  These as well as other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

1 illustrates a known prior art electrode assembly. 1 illustrates a known prior art electrode assembly. 1 shows an embodiment of an electrode according to the invention. Fig. 4 illustrates another embodiment of an electrode according to the present invention.

  Before describing the details of the present invention, it should be noted that the present invention is not limited in its application or use to the details of the construction and arrangement of parts illustrated in the accompanying drawings and description. The exemplary embodiments of the invention may be practiced or incorporated in other embodiments, variations, and modifications, and may be implemented or implemented in various ways. For example, although the present invention is described in detail in connection with electrodes for percutaneous nerve stimulation, it will be understood that such electrodes have various other uses and applications, as will be apparent to those skilled in the art Let's be done.

  FIG. 3 illustrates an exemplary embodiment of an electrode according to the present invention. Electrode 500 includes a non-conductive substrate 501, which may be composed of any well-known material such as FR4 fiberglass or polyamide. The substrate has a lateral width w, the top surface 510 includes a recess 512 that surrounds the opening 502, and the opening extends through the substrate. A conductive trace material 503, such as copper, is disposed through the opening 502 and over the entire recess 512 in the top surface 510. As used herein, the term “trace material” is intended to mean anything that has the ability to conduct electricity to form a circuit when an electrical component is soldered thereto, and is optional. Types of trace elements / materials, conductive pads, and the like. The trace material is electrically coupled to a power source (not shown) by well known methods. This embodiment further includes a second conductive material 515 that is inert or more resistant to corrosion, preferably gold or gold / nickel, which can be achieved via a well-established ENIG process. As shown, the entire top surface 514 of the trace material 503 is covered and applied through a smaller opening 502a that extends through the trace material. Adjacent to at least a portion of the first surface 510 of the non-conductive substrate and adjacent to the top surface 518 of the second conductive material 515 or over the first conductive material, A layer of third conductive material 513 that is either more or more resistant to corrosion is disposed. Material 513 spans width x such that it extends beyond the top surface of trace material 503 on all sides as illustrated in p1 and p2 of FIG. In a preferred embodiment, the third conductive material 513 is a silver ink that can be applied directly by known screen printing techniques.

  A hydrogel 505 is applied over a portion of the top surface 516 of the third conductive material 513. As illustrated in the embodiment of FIG. 3, the trace material 503 and the hydrogel 505 are laterally offset from each other by a distance p2. “Laterally offset” means that no portion of the hydrogel is positioned directly above any portion of the trace material. In this way, any imperfections in the application of materials 513 and 515 are less likely to move the hydrogel to reach the trace material compared to when the hydrogel is placed directly over the trace material. Become.

  Finally, a preferred embodiment of the present invention similar to that of FIG. 3 but incorporating additional features is shown in FIG. The electrode 600 of FIG. 4 also illustrates an additional layer 601 such as foam 601 or polyurethane, which layer is both the exposed upper surface 510 of the non-conductive substrate and the upper surface 516 of the silver layer 513. Laminating directly on top substantially encloses the hydrogel 505 but leaves the top surface 610 of the hydrogel exposed. This method prevents the laterally offset hydrogel from moving laterally and further reduces the chance that the hydrogel contacts the trace element.

  A short-term stability test was performed on the electrode configured as shown in FIG. 1 and the electrode configured as shown in FIG. In the configuration shown in FIG. 1, the electrode worked but was highly corroded due to manufacturing variations when applying an inert material intended to keep the hydrogel and the copper below it separated. It was recognized as an “unstable” design. Twenty electrodes sealed in a heat-sealed foil bag were tested in a 50 ° C. aging accelerated environment chamber. Within 3 days, all the electrodes exhibited a green color indicating corrosion. When a similar stability test was performed on 20 electrodes configured as shown in FIG. 4, no corrosion was observed even after 34 days. The results of these stability tests indicate that the electrode of the present invention is a significant improvement.

  In one preferred embodiment, the electrodes described herein are incorporated in US patent application Ser. No. 11 / 941,508, filed Nov. 16, 2007, which is hereby incorporated by reference in its entirety. It may be incorporated into a percutaneous nerve stimulation patch of the kind as illustrated and described.

  While the above describes particular embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof. Accordingly, the scope of the invention is limited only as set forth in the appended claims.

Embodiment
(1) A non-conductive substrate comprising a top surface and at least one channel penetrating the non-conductive substrate;
A conductive trace material disposed adjacent to at least a portion of the top surface of the non-conductive substrate and extending through the channel and adapted to be electrically coupled to a power source; ,
A second conductive material that is inert or more corrosion resistant than the trace material, the second conductive material being disposed adjacent to and covering the entire top surface of the trace material; ,
A third conductive material that is inert or more resistant to corrosion than the trace material and is adjacent to and covers the entire top surface of the second conductive material; A third conductive material disposed over a portion of the top surface of the non-conductive substrate surrounding
A conductive hydrogel disposed adjacent to a portion of the top surface of the third conductive trace material,
The electrode, wherein the conductive hydrogel is laterally offset from the trace material.
(2) The electrode according to embodiment 1, wherein the upper surface of the non-conductive substrate includes a recess, and the at least one channel is disposed in the recess.
(3) The electrode according to embodiment 2, wherein the entirety of the conductive trace material is disposed in the recess.
(4) The electrode according to embodiment 3, wherein the entire second conductive material is disposed in the recess.
(5) The electrode according to embodiment 1, wherein the trace material is made of copper.
(6) The electrode according to embodiment 5, wherein the second conductive material is made of gold or gold / nickel.
(7) The electrode according to embodiment 6, wherein the third conductive material is made of silver.
8. The electrode according to embodiment 1, further comprising a foam material disposed so as to substantially surround the hydrogel adjacent to at least a portion of the top surface of the third conductive material.
(9) A non-conductive base material comprising a top surface, a bottom surface, and at least one channel extending through the non-conductive base material, and made of a flexible material. A substrate;
A copper trace material disposed adjacent to at least a portion of the top surface of the non-conductive substrate, extending through the channel and configured to be electrically coupled to an electrode power source;
A second conductive material disposed adjacently over the top surface of the trace material and composed of gold or gold / nickel;
A third conductive material arranged adjacent to and covering the upper surface of the second conductive material, and made of silver;
And a conductive hydrogel disposed adjacent to and covering at least a portion of the upper surface of the third conductive material and offset laterally from the trace material.
10. The electrode of embodiment 9, further comprising a foam material that substantially surrounds the hydrogel but leaves the top surface of the hydrogel exposed.

(11) The electrode according to embodiment 9, wherein the upper surface of the non-conductive substrate includes a recess, and the at least one channel is disposed in the recess.
12. The electrode according to embodiment 11, wherein the entire conductive trace material is disposed within the recess.
(13) The electrode according to embodiment 12, wherein the entire second conductive material is disposed in the recess.

Claims (8)

A non-conductive substrate comprising a top surface and at least one channel penetrating the non-conductive substrate;
A conductive trace material disposed adjacent to at least a portion of the top surface of the non-conductive substrate and extending through the channel and adapted to be electrically coupled to a power source; ,
A second conductive material that is inert or more corrosion resistant than the trace material, the second conductive material being disposed adjacent to and covering the entire top surface of the trace material; ,
A third conductive material that is inert or more resistant to corrosion than the trace material and is adjacent to and covers the entire top surface of the second conductive material; A third conductive material disposed over a portion of the top surface of the non-conductive substrate surrounding
An electrode comprising a conductive hydrogel disposed adjacent to a portion of the upper surface of the third conductive materials,
The electrode, wherein the conductive hydrogel is laterally offset from the trace material.   The electrode of claim 1, wherein the top surface of the non-conductive substrate includes a recess, and the at least one channel is disposed in the recess.   The electrode of claim 2, wherein the entirety of the conductive trace material is disposed in the recess.   The electrode according to claim 3, wherein the entirety of the second conductive material is disposed in the recess.   The electrode of claim 1, wherein the trace material is composed of copper.   The electrode of claim 5, wherein the second conductive material is composed of gold or gold / nickel.   The electrode according to claim 6, wherein the third conductive material is made of silver.   The electrode of claim 1, further comprising a foam material disposed to substantially surround the hydrogel adjacent to at least a portion of an upper surface of the third conductive material.

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